Hadronic Spin Dependence and the Use of Coulomb-Nuclear Interference as a Polarimeter

TL;DR

This paper examines the potential of Coulomb-nuclear interference as an absolute polarimeter for proton beams, focusing on the uncertainties caused by the hadronic spin-flip amplitude and how to constrain it.

Contribution

It analyzes the impact of the hadronic spin-flip amplitude on Coulomb-nuclear interference measurements and discusses methods to constrain this uncertainty for precise polarization measurements.

Findings

Constraints on the spin-flip amplitude from differential cross-section data.

Constraints from measurements of the double transverse spin asymmetry A_{NN}.

Implications for achieving 5% polarization measurement accuracy at RHIC.

Abstract

Coulomb-nuclear interference in the single transverse spin asymmetry A_N is often considered as a possible absolute polarimeter for proton beams. The main uncertainty in this is the unknown hadronic spin-flip amplitude. This uncertainty is analyzed here in the context of the challenge of a 5% polarization measurement at RHIC. Possible constraints on the spin-flip amplitude from measurements of the differential cross-section and the double transverse spin asymmetry A_{NN} are discussed.